Paper feed mechanism



Jan. 1958 E. E. BENNETT ETAL ,8 9,7

PAPER FEED MECHANISM Original Filed Feb. 2, 1953 INVENTORS. EUGENE E. BENNETT a BY MILTON v scoz ZAFAVA ATTORNEY States PAPER FEED MECHANISM Eugene E. Bennett and Milton V. Scozzafava, Temple City, Calif., assignors to Clary Corporation, a corporation of California 7 Claims. (Cl. 197-138) This invention relates to paper feeding mechanisms and has particular reference to paper feeding mechanisms for machines commonly known as adding-listing machines which are capable of adding and subtracting or otherwise calculating, and recording the factors and results of such calculations. However, it is to be understood that at least certain aspects of the invention may be applicable to other types of machines embodying paper feeding mechanisms.

In machines of the above type, a rotatable platen is generally provided to advance a paper sheet or tape past a printing station. The platen is intermittently advanced, and in order to hold the paper in intimate contact with the surface thereof, pressure rolls are generally provided. The latter are pressed by springs or other devices toward the surface of the platen.

The force exerted by the pressure rolls against the platen is generally so arranged that adequate friction will exist between the platen and the paper to prevent slippage during the intermittent advancement of the platen. Too great a pressure, however, will tend to flaten the platen or pressure rolls when the machine is at rest since one or both are generally constructed of rubber or plastic. Also such pressure tends to unduly load the operating mechanism and to cause excessive wear of the platen and pressure rolls as well as the bearings therefor. Too little pressure will obviously permit slippage of the paper.

However, factors are frequently encountered which may vary the resistance to the feeding of the paper so that, although the pressure exerted by the pressure rolls may be adequate to normally prevent slippage, such slippage may be encountered under abnormal conditions. For example, when a new roll of paper is placed in the machine the increased inertia developed by the mass of the new roll becomes considerable, especially at relatively high rates of speed, thus tending to cause slippage. Likewise, should a roll be larger than its intended size or be out-of-round, it may rub on surrounding portions of the machine, causing it to exert an undue drag on the paper which may be sufiicient to cause slippage.

It therefore becomes a principal object of the present invention to provide a paper feed mechanism for machines of the above type which is capable of feeding a paper strip or sheet without slippage.

Another object is to provide a platen pressure roll construction in which the pressure of the roll or rolls toward the platen automatically varies in proportion to the drag exerted by or against the paper.

Another object is to automatically reduce the pressure exerted by pressure rolls against a platen when the machine is at rest.

The manner in which the above and other objects of the invention are accomplished will be readily understood on reference to the following specification when read in conjunction with the accompanying drawings, wherein:

Fig. 1 is a sectional view through the printing and paper feeding instrumentalities of an adding-listing ma- 2,819,783 Patented Jan. 14, 1958 chine, embodying a preferred form of the present invention.

Fig. 2 is a rear view of the paper trough and one of the feed rollers, and is taken in the direction of the arrow A in Fig. 1.

Fig. 3 is a front view of the paper trough and a second one of the feed rollers, and is taken in the direction of the arrow B in Fig. 1.

Fig. 4 is a transverse sectional view through part of the trough and the rear feed roller, and is taken along line 4-4 of Fig. 2.

The present application is a division of the co-pending Bennett et al. patent application, Serial No. 334,632, filed on February 2, 1953, and entitled, Calculating Machine, now Patent No. 2,744,682. Reference is hereby made to said co-pending application for a complete disclosure of an adding-listing machine in which the present invention is embodied.

The printing device forming part of the aforementioned adding-listing machine comprises a series of type wheels, one of which is shown at 81. The latter are entrained with respective ones of a series of actuator gears, one of which is shown partly at 88, which are differentially advanced under control of suitable racks and a keyboard (not shown). The wheels 81 have a series of type characters arranged around the periphery thereof, such type progressing in value from 0 to 9, and are so entrained with actuator gears 88 that they will print a digit corresponding to the incremental advancement of the respective gears.

Each type wheel 81 is rotatably mounted on an individual arm 82 which is loosely keyed on a printer control shaft 83. A spring 84 is teusio-ned between each arm 82 and a suitable part of the frame to urge the arm and its wheel toward an intermittently rotatable platen 23 around which a paper tape 22 is fed. Each type wheel 81 has integral therewith a gear 86 meshed with an idler 87 also rotatably mounted on the respective arm 82.

Except during printing operations, the arms 82 are held against the action of their springs 84 by the shaft 83 so as to maintain the idlers 87 in mesh with the gears 88.

During a printing operation, the printer control shaft 83 is rocked clockwise to permit springs 84 to rock the arms 82 into contact with a printing ribbon and tape 22 at the printing station P to print an appropriate amount on the tape. Immediately thereafter the arms 82 are returned by the shaft 83 to their initial positions, as shown, and the platen 23 is immediately advanced to position a new paper space at the printing station.

The paper tape 22 is supplied from a supply roll 133 rotatably mounted on a shaft 134' suitably supported by the machine framework in a manner not shown. The paper tape, as it is passed from the supply roll, is guided over and around a feed or pressure roller 134 and into contact with the surface of the platen 23. The tape thereafter passes over a second feed or pressure roller 135, past the printing station P and thereafter under a tear-off bar 160.

The pressure roller 135 (see also Fig. 3) comprises two spaced wheels whose peripheries are serrated, the wheels being integral with an axle 135a. The axle is rotatably mounted in bearings formed in ears 136 depending from a combined roller cradle and paper trough 137. The latter is pivotally mounted on a stationary cross rod 138 supported by spaced frame plates 161 and 162 and is urged clockwise by a light tension spring 140 extending between the trough and a stationary rod 141 whereby to lightly press the roller 135 toward the platen.

The roller 134 (see also Fig. 2) has reduced bearing shank portions 134a at opposite ends thereof, the latter being capable of rolling and/or rotating in contact with spaced guide-ways or tongues 139 extending rearwardly from the trough member 137. The guideways are substantially linear and extend at an acute angle to a line tangent to the point of contact between the platen 23 and the surface of the roller 134. A light tension spring 142 extends between a peripheral groove 142a formed in the roller 134, intermediate its ends, and the pivot rod 138 to normally and yieldably maintain the roller 134 in light contact with the paper tape at a point where the latter touches the platen. It will be noted that since the spring 142 is located midway between the ends of the roller 134, the latter will substantially effect equalization of pressures along the length thereof.

The foregoing construction insures an intimate contact between the paper and the platen to eliminate slippage between these parts as the platen is intermittently advanced. That is, as the platen is rotated, any drag exerted on the paper as it passes around the roller 134 due, for example, to the inertia of the paper roll 133, will cause the roller to roll down the inclined guideways formed by the tongues 139, thus causing a wedging action which forces the roller against the platen to increase the frictional grip upon the paper. At the same time, this wedging action tends to rotate the trough 137 in a clockwise direction to additionally force the pressure roller 135 against the paper. This feature is self-adjusting in that asmore or less drag is applied to the paper the latter will be forced more or less against the platen by both of the rollers 134 and 135.

In order to normally insure sufficient frictional engagement of the paper tape with the platen, a leaf spring 143 is attached to a part 143a of the machine framework. The latter exerts a constant drag against the periphery of the supply roll 133 and against the tape whenever the latter is advanced by the platen.

Although we have described our invention in detail and have therefore used certain specific terms and language herein, it is to be understood that the present specification is illustrative rather than restrictive and that changes and modifications may be made without departing from the spirit or scope of the invention as set forth in the claims appended hereto.

Having thus described the invention, what we desire to secure by United States Letters Patent is:

1. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a pressure roller, spaced guideways on which said pressure roller is adapted to both roll and rotate, said guideways each extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, and means for guiding said strip around said pressure roller sufliciently to enable any drag exerted on said strip to urge said roller toward said platen.

2. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a cradle, means forming a pivotal support for said cradle, a pressure roller, substantially linearly extending guideways on said cradle upon which said pressure roller is adapted to both roll and rotate, said guideways being located on one side of said pivotal support and extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, means for guiding said strip around said pressure roller, and a second pressure roller carried by said cradle, said second roller being located on the side of said pivotal support opposite from said first mentioned roller.

3. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a cradle, means forming a pivotal support for said cradle, a pressure roller, substantially linearly extending guideways on said cradle upon which said pressure roller is adapted'to both roll and rotate, said guideways being located on one side of said pivotal support and extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, means for guiding said strip around said pressure roller, a second pressure roller carried by said cradle, said second roller being located on the side of said pivotal support opposite from said first mentioned roller, and spring means urging said pressure roller in the direction of convergence of said guideways and said line.

4. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a cradle, means forming a pivotal support for said cradle, a pressure roller, substantially linearly extending guideways on said cradle upon which said pressure roller is adapted to both roll and rotate, said guideways being located on one side of said pivotal support and extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, means for guiding said strip around said pressure roller, a second pressure roller carried by said cradle, said second roller being located on the side of said pivotal support opposite from said first mentioned roller, and spring means for urging said cradle about said pivotal support to force said second roller against said platen.

5. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a cradle, means forming a pivotal support for said cradle, a pressure roller, substantially linearly extending guideways on said cradle upon which said pressure roller is adapted to both roll and rotate, said guideways being located on one side of said pivotal support and extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, means for guiding said strip around said pressure roller, a second pressure roller carried by said cradle, said second roller being located on the side of said pivotal support opposite from said first mentioned roller, spring means for urging said cradle about said pivotal support to force said second roller against said platen, and spring means for urging said pressure roller in the direction of convergence of said guideways and said line.

6. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a pressure roller, bearing portions of reduced diameter at opposite ends of said pressure roller, substantially linearly extending guideways on which said bearing portions are adapted to both roll and rotate, said guideways extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, means for guiding said strip around said pressure roller sufficiently to enable any drag exerted on said strip to urge said roller toward said platen, and a spring connected to said pressure roller midway between the ends thereof for urging said pressure roller in the direction of convergence of said guideways and said line.

7. In a calculating machine having a rotatable platen, means for maintaining a paper strip in contact with said platen comprising a pressure roller, guideways upon which said pressure roller is adapted to both roll and rotate, said guideways extending at an acute angle to a line tangent to the point of contact of said platen and said pressure roller, means for guiding said strip around said pressure roller sufiiciently to enable any drag exerted on said strip to urge said roller toward said platen, and means exerting a drag on said paper strip on the side of said pressure roller remote from said platen.

References Cited in the file of this patent UNITED STATES PATENTS 840,384 Scoggin Jan. 1, 1907 1,517,505 Hess Dec. 2, 1924 2,005,450 Bower June 18, 1935 

